Moving toward the deployment of CO2-free hydrogen

Hydrogen produced using a method that substantially reduces CO2 emissions is referred to as CO2-free hydrogen. Like other renewable energies such as solar and wind power, CO2-free hydrogen contributes to a considerable reduction in CO2 emissions, and has therefore attracted attention as a technology that can help prevent global warming.
Tokyo Gas is broadly examining technologies that can contribute to efficient and large-scale production, transportation, storage and usage of CO2-free hydrogen, and looking into the picture of a future society powered by hydrogen.

Objectives of developing technology that supports the production, transportation, storage and usage of CO2-free hydrogen

CO2 released when burning fossil fuels has been identified as the primary cause behind global warming, and this has raised the importance of reducing CO2 emissions. Renewable energies such as solar and wind power have been progressively introduced with the aim of cutting CO2 emissions, but their power output is largely dependent on weather conditions, which results in the difficulty in controlling their power generation output. At the same time, power generation driven by CO2-free hydrogen allows for transportation and storage of the hydrogen, and is distinguished by flexible power generation through output adjustments. Tokyo Gas is conducting a broad technical examination of the various methods being considered at each stage of the production, transportation, storage and usage of CO2-free hydrogen. In this way, it is looking for optimal energy supply systems for its customers.

Production methods for CO2-free hydrogen

The two principal production methods for CO2-free hydrogen are outlined below

Hydrogen production based on renewable energy

Water is electrolyzed using electricity generated from renewable energy sources such as solar and wind power, of which there can be a surplus in Japan and ample supply overseas, thus resulting in CO2-free hydrogen.

Hydrogen production from fossil fuel with the utilization of CCS technology

Hydrogen is produced from low-cost fossil fuels such as brown coal, and the CO2 released as part of this process is separated and collected, and stored underground using Carbon Capture and Storage (CCS) technology, thus resulting in CO2-free hydrogen.

Transportation and storage methods for CO2-free hydrogen

In its regular form, hydrogen is a gas with an extremely low energy density. For this reason, various methods have been considered to transport and store hydrogen in different forms. The three most commonly considered methods are outlined below.

Liquefied hydrogen

This refers to CO2-free hydrogen cooled at -253ºC and turned into a liquid state for the purpose of transportation and storage.

Methylcyclohexane (MCH)

CO2-free hydrogen is converted into methylcyclohexane by binding it to toluene for the purpose of transportation and storage. Before usage, the CO2-free hydrogen and toluene are separated again into individual components.

Ammonia (NH3)

CO2-free hydrogen is synthesized with nitrogen (N2) in the air to produce ammonia (NH3)
for the purpose of transportation and storage. In addition to reversing into hydrogen, an alternative option is to use it directly as a fuel.

Usages of CO2-free hydrogen

Many usages for CO2-free hydrogen have been considered, including supply to fuel-cell vehicles, and power generation driven by hydrogen gas turbines, pure hydrogen fuel cells, or ammonia gas turbines.

Research and development toward achievement of low cost and high efficiency CCS

Carbon Capture and Storage (CCS) is projected to be widely adopted as a technology that significantly reduces CO2 emissions and thus contributes to the prevention of global warming. It is also a technology that is required when manufacturing CO2-free hydrogen from fossil fuels such as brown coal. Tokyo Gas is engaged in the development of technology that efficiently achieves CCS at a low cost.
As part of such efforts, we have partnered with the Research Institute of Innovative Technology for the Earth (RITE) to conduct joint research in technology that converts CO2 into microbubbles and allows larger amounts of CO2 to be stored underground. This technology makes it possible to efficiently store large amounts of CO2 into a limited space of geological layers while reducing CCS costs.

Filter for the generation of CO2 microbubbles

Moving toward the deployment of a CO2-free hydrogen supply chain

Tokyo gas is taking a broad look at technologies covering the entire supply chain for large-scale and efficient production, transportation, storage and usage of CO2-free hydrogen (CO2-free hydrogen supply chain), while examining the picture of a future society powered by hydrogen.